Mascara packaging commonly comprises a container in the form of a cylindrical bottle having a neck with threaded finish. The neck has an orifice through which the bottle is filled and through which a brush-rod assembly is inserted. The brush rod-assembly depends from a threaded closure that fits onto the threaded neck finish. Furthermore, typical mascara packaging comprises a wiper situated in the orifice of the neck. The purpose of the wiper, as is well known in the art, is to clean the rod as it is withdrawn from the filled bottle by a consumer, remove excess mascara from the brush and smooth out the mascara on the brush prior to application to the eyelashes.
A typical prior art wiper is shown in FIGS. 1 and 2. Broadly defined, the wiper (100) is a hollow cylinder. Notably, the typical wiper has one retention bead (101). When the wiper is fully seated on a mascara bottle, the bead fits into a complimentary groove located on an inner wall of the bottle neck. The bead and groove stabilize the wiper in the bottle neck by opposing any movement of the wiper, as for example, when the brush passes through the wiper. A lower section (102) of the wiper is tapered such that it has a smaller diameter than that of an upper section (103) of the wiper. The lower section terminates in an lower orifice (105) and the upper section terminates in a upper orifice (104). As commonly practiced, the lower orifice diameter is typically between 0.139 and 0.163 inches, although other sizes may be in use. This range accommodates most of the brush-rod applicator assemblies currently in use.
Helpful in appreciating the present invention is an understanding of a conventional mascara filling operation in a manufacturing environment.
A packaging supplier may provide mascara bottles to a filler with the wiper already fully seated in the neck and the retention bead (101) located in the complimentary groove of the neck. This saves the filler the time and effort of having to assemble those components before filling. Most fillers opt to have the supplier insert the wipers because inserting thousands of wipers requires costly wiper-insertion equipment, requires maintenance of that equipment and the cost of any damaged components that result from machine or operator malfunction must be borne by the filler. Alternatively, the wiper and bottle may be assembled at the filling site, which saves for the filler, the cost that the supplier would charge for this service, but again this is not usually done.
In either case, with the wiper (100) fully seated in the bottle neck, a flange (106) of the wiper rests on the top of the neck. In this position, the outer surface of the upper section (103) is in substantial contact with the inner wall of the neck, all around the circumference of the upper section. This contact and the contact between the retention bead (101) and complimentary groove create an airtight seal between the wiper and the neck. Generally, the airtight seal is perfect, that is, uninterrupted all around the circumference of the upper section. However, even if the airtight seal is only nearly perfect, the airtight seal may be effective enough to hinder the movement of air between the wiper and neck. With the bottle and wiper in this configuration, a product filling tube is inserted through the upper orifice (104), down to and through the lower orifice (105) of the wiper. After the bottle is filled, the filling tube is removed.
The external diameter of the filling tube is sized to leave about 0.005 inches clearance between the fill tube and the circumference of the lower orifice (105) of the wiper (100). As noted, the wiper lower orifice diameter is typically between 0.139 and 0.163 inches, which means that the outer diameter of the filling tube is typically 0.129-0.153 inches. The 0.005 inch clearance is required so that air can escape from the bottle during filling. It is to be noted that air must escape through the wiper via the lower orifice and cannot escape between the wiper and the neck of the bottle due to the perfect or near-perfect airtight seal. Given that the wall of the filling tube may typically be 0.005 inches thick, a typical filling tube orifice may be taken to be 0.119-0.143 inches in diameter. This corresponds to a cross sectional area through which a highly viscous, tacky mascara must be forced during filling. For laminar flow of a viscous fluid, the resistance to flow in a tube is inversely proportional to the fourth power of the radius of the tube. Therefore, the smaller the fill tube radius, the more difficult and costly it is to fill a mascara bottle because higher filling pressures are needed to overcome the resistance to flow and force the mascara through the fill tube. Higher filling pressure means greater energy consumption, increased safety concerns in the manufacturing environment and a greater chance of blowing the wiper out of the bottle, causing line delays. Other disadvantages to using a smaller fill tube may be obvious to those skilled in the art. Conversely, if the fill tube orifice could be made larger, then the pressure and energy required to fill mascara bottles would decrease, while the speed and safety with which bottles may be filled would increase.